DE3842316A1

DE3842316A1 - Self-monitoring start-up circuit for electrical loads

Info

Publication number: DE3842316A1
Application number: DE19883842316
Authority: DE
Inventors: Martin Ing Grad Lieske
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-12-16
Filing date: 1988-12-16
Publication date: 1990-06-21

Abstract

A circuit arrangement of timers, the first timer being variable within predetermined limits (start-up time). Within this time, a capacitor C1 of an intrinsically safe timer is charged. After the passage of the first time the pause time begins, exclusively determined by the capacitor charge and the relay data. This pause time is monitored by a second intrinsically safe timer. The operating condition is initiated only after the activation of this last-named timer. Simultaneous switching on or overlapping of the start-up protection and of the operating protection is thus reliably prevented, even in the case of possible defects such as interruptions or short circuit of the components.

Description

Die Erfindung betrifft eine Schaltungsanordnung eines selbstüberwachenden Programmablaufes.The invention relates to a circuit arrangement of a self-monitoring program flow.

Es sind Schaltungen vorgeschlagen worden, aus Hilfsschützen und Zeitrelais, die eine bestimmte zeitliche Schaltfolge für das Hochlaufen eines Motors am Netz mit nachfolgender Umschaltung auf einen Frequenzumrichter (FU) vornehmen. Bei möglichen Defekten an den Zeitrelais oder durch Verstellen auf eine Minimalzeit kann aber bei Überschneidung, die bei einer einfachen Verriegelung möglich ist, (da die Anzugszeit eines Schützes kürzer sein kann als die Abfallzeit) der Frequenzumrichter zerstört werden.Circuits have been proposed, consisting of contactor relays and timing relays, which carry out a specific switching sequence for starting up a motor on the network with subsequent switching to a frequency converter (FU) . In the event of possible defects in the time relays or by adjusting to a minimum time, the frequency converter can be destroyed if there is an overlap, which is possible with a simple interlock (since the contactor's pull-in time can be shorter than the fall time).

Aufgabe der Erfindung ist es, eine preiswerte Schaltung zu schaffen, die in der Lage ist, einen bestimmten Programmablauf zu gewährleisten und bei möglichen Fehlern, eine Fehlschaltung, die zur Zerstörung des Frequenzumrichters führen könnte, zu verhindern. Die Erfindung ist dadurch gekennzeichnet, daß innerhalb einer ersten Zeit T 1, die zum Hochlaufen des Motors am Netz erforderlich ist, über einen Widerstand R 1 ein Kondensator C 1 aufgeladen wird. Nach Ablauf dieser Zeit schaltet der Relaiskontakt K 1 zurück auf das Relais H 1 und mit der im Kondensator gespeicherten Ladung kann das Relais H 1 anziehen bis die Kondensatorladung unter die Abfallspannung des Relais K 1 abgesunken ist. In dieser eigensicheren Zeit T 2 ist der Motor weder am Netz noch am Frequenzumrichter angeschlossen. Diese Pausenzeit kann durch mögliche Fehler nicht gegen Null gehen, da zwischen U an und U ab des Relais eine deutliche Differenz liegt. Eine zweite identische Schaltung mit R 2, C 2, K 2 und H 2 ist nachgeschaltet, die nach Ablauf der Zeit T 3 indirekt den Motor mit den Frequenzumrichter verbindet. Der Betriebszustand ist erreicht und über den Kontakt K 3 wird das erste Zeitglied stromlos geschaltet, so daß ein Neuanlauf erst wieder nach einer Gesamtabschaltung möglich ist.The object of the invention is to provide an inexpensive circuit which is capable of ensuring a certain program sequence and, in the event of possible errors, of preventing an incorrect switching which could lead to the destruction of the frequency converter. The invention is characterized in that a capacitor C 1 is charged via a resistor R 1 within a first time T 1 , which is required for the motor to start up on the network. After this time, the relay contact K 1 switches back to the relay H 1 and with the charge stored in the capacitor, the relay H 1 can pick up until the capacitor charge has dropped below the dropout voltage of the relay K 1 . During this intrinsically safe time T 2 , the motor is neither connected to the mains nor to the frequency converter. This pause time cannot go to zero due to possible errors, since there is a clear difference between U on and U down of the relay. A second identical circuit with R 2 , C 2 , K 2 and H 2 is connected downstream, which indirectly connects the motor to the frequency converter after the time T 3 . The operating state has been reached and the first timer is switched off via contact K 3 , so that a restart is only possible after a total shutdown.

Claims

1. Self-monitoring start-up circuit for electrical consumers.

A circuit arrangement of timers that monitor each other and in the event of a possible defect in the components (short circuit at Capacitors or interruption in resistors, relay coils and Capacitors) exclude switching states that lead to destruction of the switching units can cause.

The invention is characterized in that a capacitor C 1 is charged within a first time (starting time) via a resistor R 1 . After this time the relay contact K 0 switches back to relay H 1 and with the capacitor charge of C 1 (Wc = 0.5 × C × U ² ) the relay H 1 can pick up until the capacitor charge has dropped below the dropout voltage of relay H 1 is. During this intrinsically safe time, the consumer is de-energized. Another similar circuit with R 2 , C 2 , K 1 and H 2 is connected accordingly. The operating state is only initiated when the relay H 2 is switched on. H 3 is switched on via K 2 and goes into latching with K 3 . At the same time, the first timer is switched off so that a restart is only possible after a total shutdown. The operating state has been reached.

2. Self-monitoring start-up circuit according to claim 1, characterized in that the capacitor C 1 is additionally time-determining for the first timer (start-up time). R 1 can be designed to be variable to determine the time.

A minimum time is given by an additional resistor in series reached.